


Contract with a Killer

by ClassySansyPansy



Category: Undertale (Video Game)
Genre: Angst, Betrayal, Character Death, Eventual Smut, Female Chara (Undertale), Female Frisk (Undertale), Fluff, I Wrote This Instead of Sleeping, Murderer Chara (Undertale), My First Smut, Non-Canon Relationship, Protective Papyrus (Undertale), References to Undertale Genocide Route, Regret, Shameless Smut, Smut, Team Up, Verbal Frisk (Undertale), Worried Papyrus (Undertale), Worried Sans (Undertale), deal with chara, desperate sans, etc - Freeform, not dusttale sans, not killer sans, sans finally gives in, sans gives in, slight loss of sanity
Language: English
Status: In-Progress
Published: 2019-08-22
Updated: 2019-08-22
Packaged: 2020-09-23 20:49:49
Rating: Mature
Warnings: Graphic Depictions Of Violence, Major Character Death, No Archive Warnings Apply
Chapters: 2
Words: 1,572
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20346514
Author URL: https://archiveofourown.org/users/ClassySansyPansy/pseuds/ClassySansyPansy
Summary: After a few Genocide runs, Frisk eventually begins to feel bad and decides to change her ways. When she resets, she eventually gets to talk to Sans about the situation, but soon finds out that making a deal with Chara Dreemurr at the end of the first Genocide wasn't such a great idea.(WARNING!!!: Major character death.)Enjoy!!!





	1. Prologue

"I'll never agree to that, brat. Get the hell out of my house," snarled Sans Gaster, his eyes pitch black.

Chara Dreemurr stood across from him in his living room, an ominous smirk etched wide across her pale face. She fingered the point of the sharp blade she held, stepping closer. "Oh, but why not? I see no reason not to. Frisk _did _kill your precious brother countless times...not to mention all of your frien-"

"**Shut. Up.**" He clenched his fists, looking her in the eye. A faint glow of blue was just starting to show in his own eye. "I dunno who the fuck you are, appearing in my house like this...tryna convince me to break a promise...but it ain't never gonna work on me. In fact, the kid told me it was _you_ who forced her to commit all those murders. She doesn't have a single thing to do with it. It ain't in her to go genocidal. Now...you? Yeah, I'd say it's in you. Not me, not Frisk...but a violent child raised from the dead? Heh. Absolutely."

"What?" Her eyes widened, false surprise in her voice. "Me? Hahaha...good one, comedian. No, actually...it was Frisk who initiated that first route...that very first Genocide run. I didn't even know who she was until after she killed mother for the first time. I was in the shadows, all the way through the first run...all the way to the end, only introducing myself to her when she killed Flowey. _Frisk_ killed everyone, Sans...not me. _She_ reset. _She_ is the murderer, slaughtering monsterkind out of pure boredom. Reset...after reset...after reset. Who says she'll change her mind this timeline? Partner with me, and together...we'll be unstoppable against her."

There was a glint in her eye, one that the skeletal judge couldn't tell whether it was charisma or excitement...or something else, entirely. But his pupils gradually reappeared, his expression slightly softening. He sighed, unsure.

"...nobody else dies? Just her?" Sans hesitantly put his hands back in his pockets, carefully eyeing Chara.

"Of course! Only her...in fact, we could even go to straight to father afterwards and break the Barrier, if you wanted...deal?" She extended her free hand, subtly tilting her head.

"Wait a sec...what's with the knife, pal?"

"Oh, this? Well...protection against Frisk. I may be alive again, but I'm not immortal. I don't have the power of Reset, so I'm making sure she doesn't get a chance to kill me, too."

"Yeah, sure. And another thing...I knew her before the first Genocide run. Tell me why you think I would believe that she'd lie to me."

"Because you know you're desperate."

It could've been a trick of the light, but Chara might've sworn she saw him go rigid when she said that.

"Get out." He looked down.

"I-"

"I said get out. Now..."

"At least let me give you one more reason to agree."

"No."

"You wouldn't have to watch Papyrus die ever again. I'd make sure of it."

"..." Sans grunted to himself before taking a deep breath...and then, to his own surprise, he accepted her hand and firmly shook it. "Fine.Ya better not let me down, brat."

She grinned. "Great! We have a deal, then! I promise you won't regret it..._cross my heart_ _and hope to die_."

**Notes for the Chapter:**

> <3 I'm excited to continue writing this! Will Sans really break his promise to Toriel? Join me in the next chapter to find out.
> 
> P.s: Expect normal chapters to be longer than this one was. I only made it short because it was the Prologue. Thanks so much for reading, btw! Check in every so often to see what happens next, because I'm feeling really inspired and confident about this fic and think I'll actually finish it for once. Oh, and please feel free to comment what you think....I'd really appreciate it. :)


	2. Frisk

**Summary for the Chapter:**

> Frisk's first and possibly last encounter with Sans after she starts to feel bad and changes her mind. Chara makes another appearance.

Frisk had finally decided to talk to Toriel and tell her about her power of Reset and what had happened because of it, so far. She was a bit nervous about what the outcome would be, but Tori actually took it pretty well, hugging her several times and saying that she did the right thing for telling her. She also said she was proud of her for changing her mind, yet was extremely disappointed in her for committing the Genocides before doing so. She _was_ a bit shocked at first, she admitted...but didn't get a chance to chat more with Frisk before the teen informed her that she had something very important to do and rushed off, through the long, purple corridor of the Ruins and through the large double doors...into Snowdin.

* * *

Sans glanced over his shoulder, Papyrus's barred 'Human Halter' and a lamp behind that in the distance behind him. As he looked forward once again, he heard a familiar voice calling his name. His eye sockets immediately dimmed, and his expression hardened.

"It's the fuckin' kid, already," he mumbled, slowing his walking pace.

_"Quiet, she'll hear you talking,"_ Chara's disembodied voice whispered in his head. _"Go slow...savor it. And remember, when it's done, don't let her Soul crack an inch."_

Sans hummed a response just as Frisk neared him, seeming almost...frantic?

"Lookin' for fresh meat, buddy? Bad news, kiddo. Today I'm feeling pretty pissed off...and you look great for target practice, if ya **catch my drift. Wanna take turns?**" Sans growled, stepping so close to her they could've practically been touching.

Frisk softly glared at him, tears threatening to spill. "I'm so, so sorry, Sans...so very sorry. I have no excuses..." She suddenly stepped forward, wrapping him in a bear hug. "Please, please forgive me?"

Almost the instant she made contact with him, he roughly shoved her away. "Get the hell off me, ya damn liar! Why on earth would I effin' forgive _you_? You're a dirty brother killer, for Asgore's sake. Think I'd just conveniently forget everything you've done?"

"...I-"

"**Don't say another frickin' word. **Not one."

"But-"

He quickly raised his left arm, a blue aura flowing about his skeletal hand. All at once, Frisk was slammed into the ground, landing on her own arm..._crunch_.

"Freakin' stay down, ya lil' creep. I'll make this quick." Sans grinned, getting ready to snap his fingers.

She sobbed, holding her arm. "N-no, wait! Sans, please...I can explain!"

_"Hold up, comedian. I want to hear this," _Chara muttered to him.

He reluctantly nodded, both to her voice in his head and Frisk, scowling. "Make it fast, ya brat. I don't have all day."

Looking slightly surprised, Frisk could hardly get any words out at first. Finally, she calmed herself enough to speak.

"I-I'm so sorry."

"I didn't ask fer your apology, I told you to explain yourself."

"...I have no excuses for what I did, Sans. After...selling half my soul to Chara to-"

"**What?**"

"I gave Chara Dreemurr half of my Soul to keep going after my first Genocide. She had told me I had awakened her by murdering. She had no real vessel, and I was bored, anyway, so I felt bad for her and let her take half of my Soul so she could be reborn. I haven't seen her since that first run. I thought, maybe if I kept killing...I-"

"You fucking liar."

"W-what?"

"You're lyin' to me, pal...you're fuckin' lying, and I'm frickin' tired of your games."

"No, no! I'm-"

"Freaking untrustworthy, that's what. Do you know how you've affected me; my mind? I'm certain I have paranoia and PTSD 'cause of you, pal. Should be proud, now. I've come so, so close to ending it...but then I remember my brother. He's the only reason I keep going...the _only reason_. Ya hear me, you piece of shit? I can't even go through one night without an effin' nightmare!"

"I-"

"You didn't give her anything 'cause you felt bad for her. You gave her something because you're a power freak...a control obsessed lunatic...a megalomaniac. Ya knew you'd get your way, and that's all that mattered. You were bored, had nothin' else to do. Said so, yourself. Self-centered 'n disinterested...all it took for you to go through with countless runs of Genocide and many Resets. If you cared, you'd-"

"I do care, Sans! I care so freaking much, you have no idea! I love you and Papyrus, and I'd do anything for the inhabitants of the Underground. That's why I changed my mind. I've given up Genocide, just for monsterkind. I let myself get majorly distracted for awhile, but that's all done. It's finished. I haven't seen Chara, so I doubt I could do anything else to help her. I'm a Pacifist now...I promise, Sans. If I wasn't, you'd be long gone by now. Please...give me another chance. That's all I ask for...another chance. I won't disappoint you."

_"Don't listen to her. Like you said, she's lying. Finish her off...do it for Pappy."_

Sans shook his head, closing his eyes. This was too much to process. It felt like he could snap at any moment. Maybe Frisk had some good points, and maybe Chara did as well...but he wasn't sure. He couldn't focus enough to tell because his thoughts were racing. He mumbled to himself, covering his face, "Papyrus had died, he was dead, she did it. She killed Paps 'n denied it was 'cuz she's a selfish psycho. She...she..." He trailed off, ready to give into instinct.

Frisk muttered, "I love you, Sans...please say something."

That did it for him. His eyes snapped open, his arms bolting to his sides as a blue, magical glow illuminated his left eye.

**"How dare you lie to me. How dare you kill Papyrus!"** He snapped his fingers without hesitation, and a sharpened bone tore through the ground and straight through Frisk's heart.

**Notes for the Chapter:**

> Still a work in progress! What plot twists could lay ahead..?


End file.
